Towing device for an agricultural apparatus

ABSTRACT

A towing device for an agricultural apparatus ( 2 ), includes at least one wheel ( 6 ) which is arranged in a front area of the agricultural apparatus ( 2 ) and can rotate about an essentially horizontal wheel axle ( 8 ); a link arm ( 10 ) which is connected to the wheel axle ( 8 ) and is coupled in an articulated manner to a frame ( 4 ) arranged on the agricultural apparatus  92 ) about an essentially vertical first axis ( 12 ); and a draw bar ( 14 ) which can be coupled to a towing vehicle. A control member ( 22 ) is arranged between the draw bar ( 14 ) and the frame ( 4 ) in order to control the pivoting of the link arm ( 10 ) about the first axis ( 12 ) as the towing vehicle turns, so that the agricultural apparatus ( 2 ) turns at least less than the towing vehicle.

The present invention relates to a towing device for an agriculturalapparatus, comprising at least one wheel which is arranged in a frontarea of the agricultural apparatus and can rotate about an essentiallyhorizontal wheel axle; a link arm which is connected to the wheel axleand is coupled in an articulated manner to a frame arranged on theagricultural apparatus about an essentially vertical first axis; and adraw bar which can be coupled to a towing vehicle.

Large agricultural apparatuses must be provided with more than one wheelaxle so that the weight of the apparatus can be distributed over agreater surface area on the ground. An agricultural apparatus with morethan one wheel axle and towed by a towing vehicle is more difficult tohandle than an agricultural apparatus which is only provided with onewheel axle. A multi-axle agricultural apparatus has a tendency to makesharp turns behind the towing vehicle when the towing vehicle turns,which means that the towing vehicle has to widen the turns and turn witha large turning radius if the towing vehicle and the towed agriculturalapparatus are to avoid an obstacle. This has meant that the turningareas in a field tend to be considerably larger compared with anagricultural apparatus which is only provided with one wheel axle. It isalso more difficult to reverse with a multi-axle agricultural apparatuscompared with a single-axle agricultural apparatus.

There are often narrow passages and obstacles on fields, which increasethe requirement for smooth handling of an agricultural apparatus. Thedriver is forced to drive the towing vehicle back and forth in order toget into the desired position when working of the soil is to begin,leading to unwanted compression of the soil. Since work withagricultural apparatuses is often done under time constraints, the workwith a multi-axle agricultural apparatus is extremely demanding on thedriver.

The object of the present invention is to increase the manoeuvrabilityof an agricultural apparatus which is provided with a number of wheelaxles, so that the towing vehicle can make sharp turns with a smallturning radius without the agricultural apparatus also makingexcessively sharp turns.

This is achieved using an agricultural apparatus of the type set out inthe introduction, in which a control member is arranged between the drawbar and the frame in order to control the pivoting of the link arm aboutthe first axis as the towing vehicle turns, so that the agriculturalapparatus turns at least less than the towing vehicle.

With such a towing device, the agricultural apparatus is easy tomanoeuvre with the aid of the towing vehicle. The turning areas can bemade small, and it is easy to bring the agricultural apparatus to thedesired position when cultivation is to begin. It is also easy toreverse the agricultural apparatus since the controlled pivoting of thelink arm about the first axis means that the towing vehicle and theagricultural apparatus do not move towards each other.

The invention will be described in more detail below with reference toan illustrative embodiment shown on the attached drawings, in which

FIG. 1 shows a plan view of a towing device for an agriculturalapparatus according to the present invention, in a position in which theagricultural apparatus is being driven straight forwards,

FIG. 2 shows a plan view of the towing device according to FIG. 1, in aposition in which the agricultural apparatus is turning to the left,

FIG. 3 shows a perspective view of the towing device according to FIG.2, in which the agricultural apparatus is turning to the left, and

FIG. 4 shows a side view of the towing device according to FIG. 1.

A plan view of a towing device 1 for an agricultural apparatus 2according to the present invention is shown in FIG. 1. The towing device1 is set in a position in which the agricultural apparatus 2 will bedriven straight forwards. The agricultural apparatus 2 can be, forexample, a sowing apparatus, harrow, ring roller or the like, which isknown per se and will therefore not be described here. The agriculturalapparatus 2 comprises a frame 4 which at a front end is provided withtwo wheels 6. There are also wheels (not shown in the figure) at themiddle and/or back area of the agricultural apparatus 2. The purpose ofthe wheels 6 is to support the apparatus 2 so that the latter can bedriven across fields for cultivation and can be driven on roads whenbeing transported. Large and heavy agricultural apparatuses 2 require anumber of wheels 6 arranged on a number of wheel axles so that theweight of the agricultural apparatus 2 can be distributed over a largesurface area on the ground.

In the illustrative embodiment shown in FIG. 1, two wheels 6 arearranged to rotate on an essentially horizontal wheel axle 8 which is inturn connected to a link arm 10, which is articulated on the frame 4about an essentially vertical first axis 12. This means that when thelink arm 10 pivots about the first axis 12, the wheels 6 will turn inrelation to the frame 4 of the agricultural apparatus 2. The link arm 10is preferably essentially at right angles to the wheel axle 8. As isshown in FIG. 1, the first axis 12 intersects the wheel axle 8, whichmeans that the centre of turning of the wheels 6 lies between the twowheels 6. The link arm 10 extends between the wheels 6. It is possible,however, to arrange the wheel axle 8 at another place along the link arm10.

The link arm 10 and thus the wheels 6 pivot about the first axis 12 whenthe towing vehicle, such as a tractor (not shown), turns, for example inorder to turn round or to avoid an obstacle. The agricultural apparatus2 can be coupled to the towing vehicle with the aid of a draw bar 14which is connected to the link arm 10 via a coupling element 16.

The coupling element 16 is articulated on the link arm 10 about a secondessentially vertical axis 18. The draw bar 14 is connected to thecoupling element 16 via a hinge 20, which only allows the draw bar 14 topivot upwards and downwards in relation to the coupling element 16. Whenthe draw bar 14 is pivoted to the right or left, the coupling element 16will follow the movement of the draw bar 14.

The towing device 1 comprises a control member 22 which, about a thirdessentially vertical axis 24, is articulated on the coupling element 16,and, about a fourth essentially vertical axis 26, is articulated on theframe 4 of the agricultural apparatus 2. The control member 22 controlsthe pivoting of the link arm 10 about the first axis 12 when the towingvehicle turns, so that the wheels 6 are understeered in relation to theturning of the towing vehicle. Thus, the agricultural apparatus 2 doesnot turn to the same extent as the towing vehicle, which means that theagricultural apparatus 2 will widen the turn. It is therefore easier tomanoeuvre the agricultural apparatus 2 on fields and duringtransportation of the agricultural apparatus 2 on roads. The second andthird axes 18, 24 are preferably parallel and arranged at a distancefrom each other. This is achieved with a projection 28 which is arrangedon the coupling element 16 and on which the control member 22 isarranged in an articulated manner about the third axis 24. Arranged onthe frame 4 there are two lugs 30 on which the control member 22 isconnected in an articulated manner about the fourth axis 26.

FIG. 2 shows a plan view of the towing device 1 according to FIG. 1, ina position in which the agricultural apparatus 2 is turning to the left.The towing vehicle will pivot the link arm 10 about the first axis 12via the draw bar 14 and the coupling element 16, so that the wheels 6will turn in the direction in which the towing vehicle turns. However,the control member 22 will limit the pivoting of the link arm 10 aboutthe first axis 12, so that the wheels 6 and thus the agriculturalapparatus 2 will turn less than the towing vehicle.

FIG. 3 shows a perspective view of the towing device 1 according to FIG.2, in which the agricultural apparatus is turning to the left. It willbe clearly seen here how the link arm 10 is articulated on the frame 4of the agricultural apparatus 2. The first essentially vertical axis 12extends above the periphery of the wheels 6, so that the wheels 6 passfreely under the frame 4 of the agricultural apparatus 2 as the wheels 6turn.

A side view of the towing device 1 according to the invention is shownin FIG. 4. This figure also shows that the first axis 12 extends abovethe periphery of the wheels 6.

It is conceivable for the control member 22 to be adjustable so that thelength of the control member 22 can be changed, or the control member 22can be made with a number of holes which allow said control member 22 tobe arranged at different positions (not shown) on the third or fourthaxis 24, 26. This means that the understeering of the towing device Ican be varied.

It is also possible to arrange two towing devices 1 on the agriculturalapparatus 2. For the towing devices 1 to cooperate with each other; aparallel bar can be arranged between the link arms 10 of each towingdevice 1 (not shown). The figures show two wheels 6 arranged on thewheel axle 8. However, it is possible for one, three or four wheels 6 tobe arranged on the wheel axle 8. The coupling element 16 can be made inone piece with the draw bar 14.

What is claimed is:
 1. Towing device for an agricultural apparatus (2),comprising at least one wheel (6) which is arranged in a front area ofthe agricultural apparatus (2) and can rotate about an essentiallyhorizontal wheel axle (8); a link arm (10) which is connected to thewheel axle (8) and is coupled in an articulated manner to a frame (4)arranged on the agricultural apparatus (2) about an essentially verticalfirst axis (12); and a draw bar (14) which can be coupled to a towingvehicle, characterized in that a control member (22) is arranged tocontrol the pivoting of the link arm (10) about the first axis (12) asthe towing vehicle turns, so that the agricultural apparatus (2) turnsat least less than the towing vehicle; in that a coupling element (16)is coupled in an articulated manner on the link arm (10) about a secondessentially vertical axis (18); in that the control member (22) iscoupled in an articulated manner on the coupling element (16) about athird essentially vertical axis (24), and in that the control member(22) is coupled in an articulated manner on the frame (4) of theagricultural apparatus (2) about a fourth essentially vertical axis(26), so that the control member (22) controls the pivoting of the linkarm (10) about the first axis (12) as the towing vehicle turns; and inthat the draw bar (14) is connected to the coupling element (16). 2.Towing device according to claim 1, characterized in that the link arm(10) is essentially at right angles to the wheel axle (8).
 3. Towingdevice according to claim 1, characterized in that two wheels (6) arearranged on the wheel axle (8), and in that the link arm (10) extendsbetween the wheels (6).
 4. Towing device according to claim 1,characterized in that the first axis (12) intersects the wheel axle (8).5. Towing device according to claim 1, characterized in that the controlmember (22) comprises a rod.
 6. Towing device according to claim 1,characterized in that two towing devices (1) are arranged on theagricultural apparatus (2), and in that a parallel bar is arrangedbetween the link arms (10) of each towing device (1).